Baby Jace for Jace Beleren, which isn't broken, and Jace, Vyrn's Prodigy which is
Two mana for 3 damage at instant speed is the gold standard on its own, so if you can find both colors of mana regularly this is like starting the average game at 22 or so if you can pack four copies
You can activate one of Ral, Leyline Prodigy's loyalty abilities the turn he enters the battlefield
You want to hit them and double the rest of your damage for the turn, which can come from burn spells or from non first strike creatures that attacked alongside Lightning
This Psychic-type specialist switches things up with a striking pose in Team Up, claiming the honor of the set's second most valuable Trainer
Unshackling a Magic card from the need to work physically blows the design doors wide open too, so I wanted to gauge just how crazy they might be willing to get